Perception systems for use in autonomously controlling systems

ABSTRACT

A lidar sensor comprising a laser, an optical sensor, and a processor. The lidar sensor can determine a distance to one or more objects. The lidar sensor can optionally embed a code in beams transmitted into the environment such that those beams can be individually identified when their corresponding reflection is received.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

This application is a continuation of U.S. patent application Ser. No.16/998,409, filed Aug. 20, 2020, entitled “PERCEPTION SYSTEMS FOR USE INAUTONOMOUSLY CONTROLLING SYSTEMS,” which is a continuation of U.S.patent application Ser. No. 16/599,822, filed Oct. 11, 2019, entitled“PERCEPTION SYSTEMS FOR USE IN AUTONOMOUSLY CONTROLLING SYSTEMS,” nowU.S. Pat. No. 10,754,011, which is a continuation-in-part of U.S. patentapplication Ser. No. 16/298,752, filed Mar. 11, 2019, entitled“PERCEPTION SYSTEMS FOR USE IN AUTONOMOUSLY CONTROLLING SYSTEMS,” nowU.S. Pat. No. 10,444,366, which claims priority benefit under 35 U.S.C.§ 119(e) to U.S. Provisional Patent Application No. 62/692,417, filedJun. 29, 2018, entitled “PERCEPTION SYSTEMS FOR USE IN AUTONOMOUSLYCONTROLLING SYSTEMS.” Each of these applications is hereby expresslyincorporated by reference in its entirety.

BACKGROUND Field

One technical field of the present disclosure is sensing systems, andmore specifically, to perception systems for use in autonomouslycontrolling systems.

Description of the Related Art

Autonomous systems require some sensing of their environment to provideinformation and feedback to the system. For example, many designs forautonomous vehicles use light imaging, detection, and ranging (“lidar”)to measure their surroundings, identify neighboring objects, anddetermine the location and velocity of said objects. However, currentlidar devices have a range of problems including low accuracy, highcost, slow speed, and high interference from external sources. Thus,improved lidar devices are desirable not only in the field of autonomoussystems, but also in other fields of measurement.

SUMMARY

The techniques described herein provide comprehensive sensing solutionsfor autonomy applications, such as computer-assisted driving ofautomobiles, and other sensing applications. These techniques can beapplied in numerous technologies and systems, including, but not limitedto, personal and commercial ground transportation, avionics, robotics,industrial manufacturing, agriculture, mining, and mapping. The systemmay consist of a constellation, grouping, or collection of probes(including sensors or other input or sensing devices) to sense theenvironment and algorithms to interpret the data.

An example system is depicted in FIG. 1, in the context of a perceptionsystem for an automobile 1 with a central unit 10 and a plurality ofprobes 20 connected to the central unit 10. Each of the probes 20 caninclude one or more sensors. This system combines a set of features,including but not limited to the following:

-   -   Multimodality. Some or all of the sensors included in the        constellation of sensors (sometimes called a super-sensor)        contain multiple sensing modalities complementing and        reinforcing each other, which may include, but are not limited        to: lidar, radar, camera, gyroscope, kinematic and non-kinematic        position sensors, kinematic and non-kinematic velocity sensors,        global positioning systems (GPS), and ultrasonic sensors.    -   Concurrent. The different sensing modalities can be deeply        integrated into a single super-sensor, both at the hardware and        the software levels. In some embodiments, concurrent sensing by        each of one or more super-sensors, using the techniques        described herein, may replace multimodality fusion (which may        otherwise be required to combine or use simultaneously data        obtained from multiple different sensors) to boost detection        confidence (e.g., how confident the system is that it is        detecting objects in an environment being sensed by the sensors)        and measurement finesse.    -   Intelligent. In some embodiments, the sensors intelligently        allocate their resources according to the scene. For example,        areas of higher importance, such as those in the direction of        travel, may be prioritized in allocation of resources. In some        embodiments, pre-processing algorithms interpret the data and        optimize the sensor's configuration on-the-fly.    -   Flexible. In some embodiments, probing and sensing are        physically separated for better flexibility and reliability.    -   Centralized. In some embodiments, a subset of or the entire        constellation of sensors operates as a single system. Signals        from some or all the probes and the sensing modalities may        converge into one single representation of the environment,        which is then used to perceive objects in the environment.    -   Perceptive. In some embodiments, high level semantics accompany        raw 3D maps for use in interpreting the environment. A dedicated        computational engine may process the data through perception        algorithms such as clustering, classification, and tracking.    -   Open. In some embodiments, the perception system can allow for        multiple, different algorithms to run thereon, such as those        discussed herein and elsewhere.

FIG. 2 depicts a block diagram of an example system. As shown, thecentral unit 10 can communicate with a probe 20 potentially having avariety of different sensors. The central unit 10 can includeoptics/electronics components that can receive optical or electronicsignals from the probe 20 and provide initial processing of thosesignals. The optics/electronics components can also control the sensors,such as by providing instructions to measure in a particular way or in aparticular area, or alternatively to provide necessary inputs such as abeam of light to optical sensors or power to electrical actuators. Thecentral unit 10 can additionally include analog/digital converters totransform the signals from the sensors into digital form, and totransform digital instructions into analog inputs to drive variouscomponents at the probe 20. The analog/digital converters cancommunicate with a sensing engine, which can generate 3D maps and otherrepresentations of data received from the probes 20. The sensing enginecan also generate digital instructions for the probes 20, which can thenbe converted to analog form by the converters. The central unit 10 canadditionally include a perception engine that can provide a higher levelanalysis of the data provided by the probes 20. For example, theperception engine can use 3D maps and images generated by the sensingengine to identify other automobiles on a road, lane markings,pedestrians, and other features. These meaningful semantics can then beprovided to other components, such as a separate route-planning systemon an autonomous vehicle.

As noted above, the perception system can include a lidar sensor 100. Ablock diagram of a lidar subsystem, including a lidar sensor, isdepicted in FIG. 3. As shown, the lidar sensor 100 can include a laserconfigured to output a beam of light. The laser can be, but is notlimited to, a laser diode, quantum cascade laser, optical fiber laser,or distributed feedback laser. The laser can be connected or otherwisebe in optical communication with optical fibers in the form ofsingle-mode fibers, multimode fibers, tapered multimode fiber bundles,photonic crystal fibers, single mode fiber bundles, and photonic lanternmultiplexers. Optical coupling in and out of the fiber can include acollimator in the case of a single fiber output, or a lenslet array inthe case of fiber bundles or photonic lanterns. Further, a beam emittedfrom the lidar sensor 100 can be steered using electro-mechanical orelectro-optical techniques. A rotatable mirror can optionally be used,having one or two axes of rotation and being controllable by a motor orother device. A rotatable polygonal mirror can also optionally be usedfor simultaneous 2-axis beam rastering. Using these fibers, fibercouplers (including dielectric mirrors, fiber coupler cubes, fiber-opticcouplers, and metal-coated mirrors), waveguides, and/or other opticalelements such as mirrors and lenses, the beam of light from a singlelaser can optionally be steered to the plurality of probes depicted inFIG. 1, and similarly the reflected beams resulting from that beam oflight and reflected to those probes can optionally be routed back to thesame central unit 10 for processing. Thus, as shown, the central unit 10can include a plurality of transceivers that communicate with variousprobes 20. Even further, multiple probes 20 can optionally be connectedto a single transceiver, allowing for probe multiplexing signalscollected simultaneously from different moments in time, differentdirections in space, and also from multiple probes.

A variety of different lidar systems can be used with theabove-described systems. For example, a lidar sensor can include anoptical sensor, a laser, at least one phase modulator, and a processor.The optical sensor can be configured to produce a signal based at leaston receiving one or more beams of light. A laser can be configured toemit an initial beam of light, a first portion of that light beingdirected into the environment, and an internal portion being directed tothe optical sensor. The optical sensor can be configured to receive boththe internal portion and a first reflected beam of light resulting fromthe first portion of the initial beam of light being reflected at afirst point of reflection in the environment. The phase modulator can beconfigured to modulate a phase of the first portion of the first portionof the initial beam of light over a period of time with a unique code toembed the unique code into a modulated phase of the first portion of theinitial beam of light prior to it being directed into the environment.The processor can be configured to receive signals from the opticalsensor and to identify the first reflected beam of light as havingresulted from the first portion of the initial beam of light based atleast on detecting the unique code. The processor can be furtherconfigured to determine a distance to the first point of reflectionbased at least on the first reflected beam of light and the internalportion of the initial beam of light.

In a further embodiment, a lidar sensor can include an optical sensor, alaser, and a processor. The optical sensor can be configured to producea signal based at least on receiving one or more beams of light. Thelaser can be configured to emit an initial beam of light, with a firstportion of the initial beam of light being directed into the environmentin a first direction, a second portion of the initial beam of lightbeing directed into the environment in a second direction different fromthe first direction, and an internal portion of the initial beam oflight being directed to the optical sensor. The optical sensor can beconfigured to receive each of the internal portion of the initial beamof light, a first reflected beam of light resulting from the firstportion of the initial beam of light being reflected at a first point ofreflection in the environment, and a second reflected beam of lightresulting from the second portion of the initial beam of light beingreflected at a second point of reflection in the environment. Theprocessor can be configured to receive signals from the optical sensorand to identify the first reflected beam of light as having resultedfrom the first portion of the initial beam of light and the secondreflected beam as having resulted from the second portion of the initialbeam of light. The processor can further be configured to determinedistances to the first and second points of reflection based at least onthe first and second reflected beams of light and the internal portionof the initial beam of light. The time between direction of the firstportion of the initial beam of light into the environment and receptionof the first reflected beam of light by the optical sensor overlaps withthe time between direction of the second portion of the initial beam oflight into the environment and reception of the second reflected beam oflight by the same optical sensor.

In a further embodiment, a lidar sensor can include an optical sensor, alaser, and a processor. The optical sensor can be configured to producesignals based at least on receiving one or more beams of light. Thelaser can be configured to emit an initial beam of light, a firstportion of the initial beam of light being directed into the environmentand an internal portion of the initial beam of light being directed tothe optical sensor. The optical sensor can be configured to receive boththe internal portion of the initial beam of light and a first reflectedbeam of light resulting from the first portion of the initial beam oflight being reflected at a first point of reflection in the environment.The processor can be configured to receive signals from the opticalsensor and identify the first reflected beam of light as having resultedfrom the first portion of the initial beam of light based on thesignals. The processor can also be configured to determine a distance tothe point of reflection based at least on the first reflected beam oflight and the internal portion of the initial beam of light. Evenfurther, the processor can be configured to determine a radial velocityof the point of reflection relative to the lidar sensor based at leaston a time derivative of a difference in phases of the light fieldbetween the first reflected beam of light and the internal portion ofthe initial beam of light. Even further, the lidar sensor can beconfigured to determine an angular velocity of the point of reflectionrelative to the lidar sensor based at least on a Doppler shift of thefirst reflected beam of light and the determined radial velocity.

In a further embodiment, a lidar sensor can include a laser, a firstfiber coupler, an optical synthesizer circuit, a transmitter, areceiver, a second fiber coupler, and an optical sensor. The laser canbe configured to emit an initial beam of light, and the first fibercoupler can be in optical communication with the laser to receive anddivide the initial beam of light into a transmitted portion and aninternal portion. The optical synthesizer circuit can be in opticalcommunication with the first fiber coupler to receive the transmittedportion of the initial beam of light from the first fiber coupler and toadjust the phase of the transmitted portion of the initial beam oflight. The transmitter can be in optical communication with the opticalsynthesizer circuit to receive the transmitted portion with an adjustedphase from the optical synthesizer circuit and direct the transmittedportion into the environment. The receiver can be configured to receivethe reflected beam of light from the environment resulting from thetransmitted portion of the initial beam of light. The second fibercoupler can be in optical communication with the receiver and the firstfiber coupler to combine the reflected beam of light and the internalportion of the initial beam of light into a combined beam of light. Theoptical sensor can be in optical communication with the second fibercoupler to receive the second beam of light.

In a further embodiment, a method of measuring distance can be provided.A beam of light can be split into a transmitted portion and an internalportion. The phase of the transmitted portion can be modulated over aperiod of time to embed a unique time-dependent code into thetransmitted portion. The transmitted portion with the modulated phasecan then be directed into the environment, and a reflected beamresulting from the transmitted portion being directed into theenvironment can be received. The reflected beam can be identified asresulting from the transmitted portion being directed into theenvironment at least by detecting the unique code. A distance to a pointof reflection can then be estimated using the reflected beam and theinternal portion.

In a further embodiment, a method of simultaneously measuring multipledistances can be provided. A beam of light can be split into a firsttransmitted portion, a second transmitted portion, and an internalportion. The first and second transmitted portions can be directed intothe environment in different directions. Reflected beams resulting fromthe first and second transmitted portions being directed into theenvironment can then be received at a single optical sensor. Thereflected beams can be identified as resulting from the first and secondtransmitted portions being directed into the environment, and a distanceto the points of reflection can be estimated using the reflected beamsand the internal portion. The time between the directing of the firsttransmitted portion into the environment and receiving the reflectedbeam resulting from the first transmitted portion can overlap with thetime between the directing of the second transmitted portion into theenvironment and receiving the reflected beam resulting from the secondtransmitted portion.

In a further embodiment, a method of operating a lidar sensor to measurea distance to an object and a velocity of the object can be provided. Abeam of light can be split into a transmitted portion and an internalportion, and the transmitted portion can be directed into theenvironment. A reflected beam resulting from the transmitted portionbeing directed into the environment can be received. A distance to apoint of reflection can be estimated using the reflected beam and theinternal portion. Additionally, a radial velocity of the point ofreflection relative to the lidar sensor can be estimated, based at leaston a time derivative of a difference in phases of the light fieldbetween the reflected beam of light and the internal portion. Further,an angular velocity of the point of reflection relative to the lidarsensor can be estimated based at least on a Doppler shift of thereflected beam and the determined radial velocity.

In a further embodiment, a lidar sensor comprises a light sourceconfigured to generate a source light having different wavelengths. Thelidar sensor additionally comprises an optical synthesizer circuitconfigured to receive a portion of the source light, where the portioncomprises light beams having different wavelengths. The opticalsynthesizer circuit comprises a phase modulator configured to embed aunique code into at least one of the light beams. The lidar sensorfurther comprises a plurality of transceivers configured to receive fromthe optical synthesizer circuit at least one of code-embedded lightbeams having different wavelengths, to direct the at least one of thecode-embedded light beams into an environment, and to receive at leastone of reflected light beams from objects reflecting the at least one ofthe code-embedded light beams. The lidar sensor is configured to detectdistances between the objects and the transceivers using the at leastone of the reflected light beams.

In a further embodiment, a lidar sensor comprises a light sourceconfigured to generate a source light comprising a plurality of lightbeams having different wavelengths. The lidar sensor additionallycomprises a plurality of optical synthesizer circuits, where each of theoptical synthesizer circuits is configured to receive a portion of oneof the light beams having one of the wavelengths. Each of the opticalsynthesizer circuits comprises a phase modulator configured to embed aunique code into the portion of the one of the light beams. The lidarsensor further comprises a plurality of transceivers each configured toreceive from a respective one of the optical synthesizer circuits one ofcode-embedded light beams, to direct the one of the code-embedded lightbeams into an environment, and to receive a reflected light beam from anobject reflecting the one of the code-embedded light beams. The lidarsensor is configured to detect a distance between each of thetransceivers and the object using the reflected light beam.

In a further embodiment, a lidar sensor comprises a light sourceconfigured to generate a source light comprising a plurality of lightbeams having different wavelengths. The lidar sensor additionallycomprises one or more optical synthesizer circuits, wherein each of theoptical synthesizer circuits is configured to receive a portion of thesource light and to divide the portion of the source light into a firstpart and a second part, and wherein the each of the optical synthesizercircuits comprises an optical component configured to embed a uniquecode into at least the first part. The lidar sensor further comprises aplurality of transceivers each configured to receive from a respectiveone of the optical synthesizer circuits one of code-embedded lightbeams, to direct the one of the code-embedded light beams into anenvironment, and to receive a reflected light beam from an objectreflecting the one of the code-embedded light beams. The lidar sensor isconfigured to detect a distance between each of the transceivers and theobject using the reflected light beam.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features and advantages of the invention will becomeapparent from the following detailed description taken in conjunctionwith the accompanying figures showing illustrative embodiments of theinvention, in which:

FIG. 1 is a system diagram of an embodiment perception system.

FIG. 2 is a block diagram of an embodiment perception system.

FIG. 3 is a block diagram of an embodiment lidar system.

FIG. 4A depicts a lidar system using direct detection.

FIG. 4B depicts a lidar system using coherent detection.

FIGS. 5A-5H depict various lidar systems using coherent detection andsuperheterodyne techniques.

FIGS. 6A-6C depict various lidar systems using coherent detection andsuperhomodyne techniques.

FIGS. 7A and 7B depict codes that can be embedded into a phase of a beamof light.

FIG. 8 depicts a computer system.

FIG. 9 depicts a method for estimating a distance using a lidar sensor.

FIG. 10 depicts a method for detecting multiple distancessimultaneously.

FIG. 11 depicts a method for measuring a distance, radial velocity, andangular velocity.

FIG. 12 illustrates a lidar system having a light source configured togenerate a source light having multiple wavelengths and an opticalcircuit configured to embed a code in the source light for detection ofobject distances.

FIG. 13 illustrates a lidar system having a light source configured togenerate a source light having multiple wavelengths and optical circuitsconfigured to embed a code in the source light for detection of objectdistances.

FIG. 14 illustrates a lidar system having a light source configured togenerate a source light having multiple wavelengths and optical circuitsconfigured to embed a code in the source light for detection of objectdistances.

DETAILED DESCRIPTION

FIGS. 4A and 4B depict lidar systems using direct detection and coherentdetection. Lidars detect objects by actively illuminating theenvironment and measuring the intensity of the light reflected by anyencountered surfaces. Sensing techniques fall into two main camps:direct and coherent (sometimes called “indirect”). Direct detectiontechniques (depicted in FIG. 4A) may measure the intensity of thereflected light directly with an optical sensor (such as a photodiode,photoreceiver, or photodetector). Coherent detection techniques(depicted in FIG. 4B) may use an indirect method: mixing together thereceived light with part of the transmitted light on the optical sensorand measuring the interference between them with the optical sensor.

In some embodiments, coherent detection provides the followingadvantages over direct detection:

-   -   Noiseless signal amplification. Direct and coherent detection        often respond to background and electronic noise in very        different ways. In direct detection, amplifying the signal often        also amplifies the noise, without improving the signal-to-noise        ratio (SNR). In contrast, coherent detection is often capable of        amplifying the signal alone and improving the SNR.    -   Dynamic range. Direct and coherent detection differ also by        their dynamic range. In direct detection the signal is often        directly proportional to the intensity of the received light and        falls with the inverse of the squared distance of the object. In        coherent detection the signal is often directly proportional to        the amplitude of the received intensity and falls with only the        inverse of the object's distance.

Unlike some coherent detection technologies based on frequencymodulation, some lidar systems described herein detect the range ofobjects by measuring the phase of the reflected light. They canpotentially do so by solving one or more key problems that renderedcoherent detection methods not applicable before: 1) the intrinsicambiguity in mapping the phase of the light into distance; 2) theinstability of the phase of the light upon reflection from a roughsurface; 3) the Doppler shift in the frequency of the light reflected bymoving objects; 4) the narrow acceptance angle of the receiver; 5) theintrinsic indistinguishability of signals coming from differentdirections; 6) the laser's phase fluctuations due to noise.

(1) Phase ambiguity. The relative phase

ϕ between the transmitted and the received waves (having a wavelength λ)is directly proportional to the round trip distance to the object 2L:

${\Delta\phi} = {\frac{4\pi}{\lambda}L}$

In principle L could be obtained by measuring

ϕ and inverting this relationship. However, the phase increases by 360°degrees when the light travels through a distance equal to itswavelength (for example, approximately one micrometer). After that itwraps back to zero such that:

${\Delta\phi} = {\frac{4\pi}{\lambda}\left( {L\mspace{14mu}{mod}\mspace{14mu}\lambda} \right)}$

The phase of the light has effectively only “short-term memory” of thedistance traveled and by itself it could not be used to measuredistances longer than the light's wavelength.

(2) Phase instability. The phase of the light reflected by roughsurfaces changes abruptly if the object moves under the illuminatinglight even slightly. That makes the phase measurement not practical inmany situations.

(3) Doppler uncertainty. The velocity (v) of an object makes thefrequency (f) of the reflected light increase or decrease depending onwhether it's leaving or approaching the receiver:

$f_{Doppler} = \frac{v}{\lambda}$

Because the frequency shift is unknown and can suddenly change as thelidar looks at different points in space, finding the signal andtracking its phase is challenging.

(4) Slow scanning. For the interference between the transmitted and thereceived light to generate a large signal, the two waves need to overlapsufficiently well on the optical sensor. In some coherent systems, thisrequirement may significantly limit the effective field of view of thereceiver and consequently the beam scanning speed.

(5) Directional ambiguity. Some coherent lidars are not capable ofdistinguishing signals entering the optical sensor simultaneously frommultiple directions. For the same reason, other lidars in the field ofview can generate interference.

(6) Laser phase noise. In interferometric ranging the phase of thetransmitted light is effectively the length used as a reference tomeasure other distances. The intrinsic instability of the laserfrequency/phase or mechanical vibrations propagating through thetransmitter can significantly affect the raining accuracy/precision.

There are numerous possible approaches to and/or architectures for lidarsystems that can address some or all of these problems. FIGS. 5A-5Hdepict lidar sensor systems that use superheterodyne coherent detectionmethods measuring the phase of an RF beatnote (although frequency rangesoutside RF are also possible). In some embodiments, the techniquesmeasure the phase between two coincident and spatially/temporallycoherent laser beams. Factors like phase ambiguity, phase instabilityand Doppler uncertainty may affect both beams to the same extent andcancel out in a differential measurement. To do so, the beams need to beseparable yet be precisely overlapped. This is discussed in more detailherein.

FIG. 5A depicts a lidar sensor 100A including a laser 110. The laser 110can optionally be part of a central unit 10, as described above. Asfurther discussed above, the laser 110 can be separate from the othercomponents depicted in FIG. 5A. Even further, the laser 110 canoptionally be shared between multiple lidar sensors, such that one laser110 can potentially provide beams of light simultaneously to a pluralityof lidar sensor arrangements as shown in FIG. 3 (where the remainingcomponents in FIG. 5A can be provided separately to each transceiver).One or more fiber couplers can be used to propagate the beam of lightfrom a single laser to multiple subsystems. However, in otherembodiments each lidar sensor 100 can include a dedicated laser 110, asimplied by the arrangement of components depicted in FIG. 5A.

The initial beam of light from the laser 110 in FIG. 5A can be split(for example, with one or more fiber couplers 170) into three separateportions. A first portion of the beam can be directed (for example withan optical fiber) to a first frequency shifter 140. The first frequencyshifter 140 can be, for example, an electro-optical frequency shifterbased on the Pockels effect or an acousto-optic frequency shifter. Asshown, the first frequency shifter 140 can adjust or modulate thefrequency of the first portion of the beam from a frequency f₀ toanother frequency f₀+f₁. Although the frequency is depicted as beingadjusted higher, in other embodiments the frequency can be adjustedlower. More generally, the frequency can be adjusted to be a variety ofdifferent frequencies, optionally between zero and 10 GHz.

The first portion can then be directed to a first phase modulator 150.The first phase modulator 150 can be, but not limited to, a lithiumniobate crystal or waveguide. The first phase modulator 150 can beconfigured to embed a code c₁ in the phase of the first beam of lightover a period of time. As shown, the code can be substantially binary orquaternary, like a bar code. For example, the code can shift between azero degree phase for a period of time and then to a 180 degree phasefor a period of time, repeating that pattern for varying durations togenerate the code. Even further, the code can optionally be random orpseudo-random and have a sufficient length to be considered unique. Anexample code is depicted in FIG. 7A. However, other variations arepossible. For example, the phase can optionally shift 90 degrees, 45degrees, or 30 degrees. Further, the phase can be non-binary, includingmore than two possible phases.

A second portion of the beam of light from the laser 110 can bemanipulated in a similar manner as the first portion, as depicted inFIG. 5A. As shown, the second portion can be directed on an optical pathdifferent from the first portion, and can be adjusted by a secondfrequency shifter 141, adjusting the second portion to a frequency f₀+f₂that can be optionally different from the first frequency, and a secondphase modulator 151 that can be optionally configured to provide asimilar but different code c₂ to the second portion such that the twocodes are substantially orthogonal to each other. The first portion andthe second portion can then be combined by a fiber coupler 171 and thenjointly directed to a transmitter 120. In this manner, a combined beamcan be generated having a frequency f₁-f₂ and a phase-modulated codec₁c₂ (a separate component having a frequency f₁+f₂ can be ignored forthese purposes). In some embodiments the frequency f₁-f₂ can be between0 to 10 GHz. This combined beam is generated by an optical synthesizercircuit 115, which can adjust the frequency and phase of portions oflight prior to transmission into the environment. The opticalsynthesizer circuit 115 can optionally include components in addition tothe frequency shifters 140, 141 and phase modulators 150, 151 such ascollimators, mirrors, lenses, fiber couplers, delay lines, and otheroptical components that can prepare the beam for transmission. Further,although the first fiber coupler 170 is not depicted as being part ofthe optical synthesizer circuit 115 in FIG. 5A, it can optionally beconsidered to be part of the optical synthesizer circuit 115. Forexample, in another example of a lidar sensor in FIG. 5B, the functionof the fiber coupler 170A in FIG. 5A is split into two fiber couplers170B and 171B, only one of which being part of the optical synthesizercircuit 115.

The combined beam can then be directed into an environment by thetransmitter 120. The transmitter 120 can optionally include variousoptical components such as one or more lenses, mirrors, collimators, orother devices. Further, the transmitter 120 can also optionally includeadjustable components such that the first and second portions of thebeam of light can be directed in a controllable direction. For example,the transmitter 120 can optionally have an angular range of at least 180degrees, 90 degrees, or 45 degrees.

The combined beam directed into the environment can encounter an objectcausing a reflected beam that results from the first and secondportions. This reflected beam can then be received by a receiver 130 andcan be directed to an optical sensor 180. The optical sensor can alsoreceive an internal portion of the initial beam of light from the laser110. Thus, the optical sensor 180 can potentially derive informationfrom the characteristics of the reflected beam and the characteristicsof an interference between the reflected beam and the internal portionof the initial beam. The optical sensor 180 can then generate a signalindicative of the beams received and can provide that signal to acomputer system 300 (depicted in FIG. 8), and potentially through thesystem depicted in FIG. 2, for further analysis. Such analysis caninclude steps such as identifying the codes c₁ and c₂ in the reflectedbeams to identify the time of transmission of said beams. Arepresentation of the combined beam without the codes can also besynthesized electronically (digitally or in analog) by measuring andsubtracting the phase of beatnotes of each of the reflected beams withthe local oscillator, after appropriate decodings (such as removing thecodes c₁ and c₂). The combined beam can also be synthesized by squaringthe signal at the optical sensor 180, canceling out possible Dopplershifts induced by a moving object at the point of reflection. Further,comparing the phase of the received reflected beam to the beam that wastransmitted can be used to determine (and then cancel) noise caused byinstability in the laser 180, mechanical vibrations, and other effects.

Further variations on this system are also possible. For example, insome embodiments the transmitter 120 and receiver 130 can be combinedinto a transceiver with shared lenses, mirrors, or other components.Additionally, like the laser 110, the optical sensor 180 can also bepart of the central unit 10, separate from the other components depictedin FIG. 5A such as the optical synthesizer circuit 115, or be sharedbetween multiple lidar sensors. Even further, parts of the opticalsynthesizer circuit 115 can be shared between multiple lidar sensors,such as by using a single frequency shifter 140/141 to generate aportion with a shifted frequency that can be used for multiple lidarsensors.

The use of the codes c₁ and c₂ can facilitate the identification of thecombined beam among a variety of other combined beams (having differentcodes) that can be collected at a single optical sensor 180 sharedamongst a plurality of lidar sensors 100A. Thus, for example, a lidarsensor could have two sets of components (such as two opticalsynthesizer circuits 115, frequency shifters 140, phase modulators 150,transmitters 120, and/or receivers 130) each using directing separatecombined beams (which can be portions of the same initial beam from thelaser 110) to measure distances in different directions simultaneously(such that the times of transmission into the environment and receptionof a reflected beam for each set of components can overlap). It shouldalso be noted that the codes can also facilitate the identification ofreflected beams originating from the lidar sensors 100 as opposed tobeams that might be emitted by other devices such as neighboring carsthat might also include lidar sensors, such that the lidar sensors 100can operate in the presence of large numbers of other lidar sensors.

The reflected beam can be used to measure a variety of features relatingto an object at the point of reflection. For example, the reflected beamcan indicate a distance L to the point of reflection using the phase ofthe received synthetic beam Φ_(r) relative to that of the transmittedsynthetic beam Φ_(t) (along with the wavelength Λ of the syntheticbeam):

$L = {\frac{\Lambda}{4\pi}\left( {\Phi_{t} - \Phi_{r}} \right)}$

The phase of the transmitted synthetic beam Φ_(r) can be estimated bymeasuring a phase of the beam prior to being directed into theenvironment. For example, the transmitter 120 can create a reflectionthat can also be received by the optical sensor 180 for measurement.Alternatively, a portion of the beam can be measured further upstream,prior to reaching the transmitter 120.

This analysis optionally can be done after an electronic representationof the beam without the codes has been generated. The ambiguity range(due to the repeating of the phase) can be made arbitrarily large bychoosing close enough frequency shifts f₁ and f₂, leading to a syntheticwavelength (using the speed of light c):

$\Lambda = \frac{c}{f_{1} - f_{2}}$

For example, the wavelength can be greater than 300 m for f₁-f₂ lessthan 1 MHz. However, in some situations the frequency shift cannoteasily be made small enough to yield a sufficiently large wavelength.Nevertheless, the resulting ambiguity from phase differences can beresolved by measuring the delay of the propagated code from transmissionto reception, which can indicate a time-of-flight of the beam and thus adistance when compared with the speed of light. This code delay canprovide a coarse measurement of the range, and the phase difference canprovide a fine measurement of the last fraction of the distance.Combined, the coarse and the fine measurement can provide an accurateand unambiguous measurement of the distance. For example, the lidarsensor 100 can have an accuracy of 1 mm or better. Further, the lidarsensor 100 can measure to this accuracy at ranges of 10 meters, 50meters, 100 meters, 200 meters, or 500 meters.

The reflected beam can also be used to measure a velocity of the pointof reflection (for example, a velocity of an object when the point is onthe object). The velocity of the point in a radial direction from thelidar sensor 100 can be determined by using a time derivative of thedistance:

$v_{} = {\frac{\Lambda}{4\pi}\frac{d}{dt}\left( {\Phi_{t} - \Phi_{r}} \right)}$

This measurement can be facilitated using the code embedded in the beam,which allows continuous measurement, unlike other techniques that relyon discreet pulses.

The velocity of the point in an angular direction, tangential to thelidar sensor 100 can also be determined. For example, a Dopplerfrequency shift can be measured from the reflected beam, indicating atotal velocity when multiplied by the wavelength λ. The radial velocitycan then be subtracted to determine the angular velocity:

v _(⊥) =Δf _(Doppler) −v _(∥)

The reflected beam can also be used to measure a reflectivity of theobject at the point of reflection. The amplitude of the reflected beamcan indicate a reflectivity of the object when compared withexperimental results at comparable distances, using look-up tables forexample.

Further variations on the design of the lidar sensor 100 are alsopossible, as shown by example in FIGS. 5B-5H, which can be similar tothe embodiment in FIG. 5A unless indicated to the contrary, with similarnames and reference numbers indicating similar components. For example,as shown in FIG. 5B, the lidar sensor 100B can include only onefrequency shifter 140B (for instance an acousto-optic modulator, “AOM”,although other frequency shifters are also possible) and one phasemodulator (depicted as an electro-optic modulator, “EOM”, although otherphase modulators are also possible including, but not limited todual-parallel Mach-Zehnder interferometers) 150B to adjust the frequencyof a first portion of the initial beam of light and apply a code to eachof the first and second portions of the initial beam of light emitted bythe laser 110B. This initial beam of light can encounter a first fibercoupler 170B which can direct an internal portion of the beam toward anoptical sensor 160B, and direct the remaining beam to an opticalsynthesizer circuit 115B. The optical synthesizer circuit 115B caninclude a second fiber coupler 171B, splitting first and second portionsof the beam for transmission. The first portion can proceed directly toa frequency shifter 140B, then to a phase modulator 150B, and then to atransmitter 120B in substantially the same way as in FIG. 5A. Distinctfrom FIG. 5A, the embodiment in FIG. 5B can include a first opticalcirculator 190B between the frequency shifter 140B and the phasemodulator 150B, a second optical circulator 191B between the phasemodulator and a third fiber coupler 172B, and a third optical circulator192B between the third fiber coupler 172B and the transmitter 120B.However, the second portion can be directed from the second fibercoupler 171B to the second optical circulator 191B, such that it canthen pass through the phase modulator 150B in reverse relative to thefirst portion. The second portion can then be directed by the firstoptical circulator 190B to an optional delay line 200B and then to thethird fiber coupler 172B (where it can be combined with the firstportion, the coupler serving as a combiner) to be transmitted with thefirst beam portion as in FIG. 5A.

The code provided by the phase modulator 150B can be unique, such aswith a pseudo-random code as described above (although different typesof codes from spread spectrum theory can be used). This code can besufficiently random such that a delay provided by the delay line 200Bcan shift the codes applied to the first and second portions of the beamof light sufficiently for the two codes to be substantially orthogonalto each other. Thus, the processing of signals from the lidar sensor100B can be substantially the same as from the lidar sensor 100 of FIG.5A, with the exception that f₂ is zero. Nevertheless, f₁ can optionallybe adjusted in a similar manner to achieve the desired ambiguity rangefor the measured distance as discussed above with respect to FIG. 5A.

FIG. 5B also depicts an embodiment where the transmitter 120B and thereceiver 130B are combined into a single transceiver, with the thirdoptical circulator 192B directing the reflected beam from thetransceiver 120B/130B to a fourth fiber coupler 193B. The fourth fibercoupler 193B combines the reflected beam and the internal portion of theinitial beam, and directs them to the optical sensor 160B.

FIG. 5C depicts an embodiment lidar sensor 100C with similarities toboth the lidar sensors 100A, 100B of FIGS. 5A and 5B. As shown, theoptical synthesizer circuit 115C can include separate and independentpaths for each of the first and second portions of the initial beam oflight, as in FIG. 5A. However, only one frequency shifter 140C isincluded, such that only one of the two portions has its frequencyshifted, as in FIG. 5B.

FIG. 5D depicts an embodiment lidar sensor 100D substantially similar tothe lidar sensor 100A in FIG. 5A, with some minor differences. Forexample, a transceiver 120D/130D can replace the separate components inFIG. 5A.

FIG. 5E depicts an embodiment lidar sensor 100E substantially similar tothe lidar sensor 100D in FIG. 5D, but including only one frequencyshifter 140E. As shown, the optical synthesizer circuit 115E can includea partially-reflective mirror 210E between the frequency shifter 140Eand a first phase modulator 150E, such that a first portion of theinitial beam can pass through these two components as in FIGS. 5A-5D.The second portion of the initial beam can be separated from the firstportion here by the reflection at the in-line partial retroreflector210E (which function as an in-line fiber coupler), instead of at afiber-optic fiber coupler as depicted in the figures for the previousembodiments. The second portion can then pass through the frequencyshifter 140E a second time, yielding a frequency f₀+2f_(m) (with thefirst portion's frequency at f₀+f_(m)). The second portion can then bedirected by the optical circulator 190E to a second phase modulator 151Eto apply a code and pass the beam to a second fiber coupler 170E forrecombination with the first portion prior to transmission.

FIG. 5F depicts an embodiment lidar sensor 100F similar to the lidarsensor 100E in FIG. 5E, but using only a single phase modulator 150F anda different method for separating the first and second portions of theinitial beam. As shown, instead of a partially-reflective mirror betweenthe frequency shifter 140F and the phase modulator 150F, a second fibercoupler 171F can be included, and a second optical circulator 191F canbe provided between the phase modulator 150F and a fiber coupler 172Fprior to the transceiver 120F/130F. Thus, the second portion of theinitial beam can be separated at the second fiber coupler 171F, whichcan direct the second portion past the phase modulator 150F to thesecond optical circulator 191F. The second portion can then be directedin a reverse direction through the phase modulator 150F and thefrequency shifter 140F (yielding a frequency of f₀+2f_(m) as in FIG.5E). Finally, the first optical circulator 190F can direct the secondportion through a delay line 200F prior to recombination with the firstportion.

FIG. 5G depicts an embodiment lidar sensor 100G similar to the lidarsensor 100E in FIG. 5E, but providing both the first and second portionswith the same code. As shown, a single phase modulator 150G can beprovided downstream from the second fiber coupler 171G, between thefiber coupler and a second optical circulator 191G just before thetransceiver 120G/130G, such that both portions receive the same code.

FIG. 5H depicts an embodiment lidar sensor 100H that is furthersimplified to only include one frequency shifter 140H and one phasemodulator 150H, with one portion of the initial beam of light remainingunshifted. Instead, the initial beam of light from the laser 110H issplit only once at the first fiber coupler 170H, into a transmittedportion and an internal portion. The transmitted portion is directed toa frequency shifter 140H that, unlike the previously describedembodiments, provides two superimposed frequency modulations onto thetransmitted portion. As shown, frequencies of f_(m) and f_(m)+Δf areused to shift the transmitted portion (starting with a frequency of f₀).Thus, a combined beam can then be generated having a frequency of Δf.The combined beam can then be directed to the phase modulator 150H,which applies a single code prior to passing the beam along toward thetransceiver 120H/130H. Thus, using a combined frequency Δf and a singlecode, the analysis of the reflected beam can be similar to thosediscussed above.

Thus, a variety of different lidar sensors are possible and othercombinations and permutations of the embodiments described above will beunderstood to one of skill in the art as part of the disclosure herein.

In addition to the superheterodyne lidar sensors described above,superhomodyne lidar sensors can also be used to measure the phase of thereflected light from the direct current (“DC”) signal it generates on anoptical sensor. FIGS. 6A-6C depict different lidar sensors using thesetechniques, with certain components being similar to those in FIGS.5A-5H unless otherwise stated.

FIG. 6A depicts a lidar sensor 100I with a layout and mode of operationsubstantially similar to the lidar sensor 100A in FIG. 5A, but withoutfrequency shifters. Additionally, the lidar sensor 100I can includephase modulators 1501, 1511 that provide a different code c₁ to thefirst portion of the initial beam of light to be transmitted. As shown,the code c₁ can be the combination of a “bar code” (such as thatdescribed previously and shown as a pseudo-random noise code in FIG. 7A)and a periodic pattern such as sawtooth phase modulation depicted inFIG. 7A, yielding the combined code c₁ depicted in FIG. 7A. Again, thecodes c₁ and c₂ can be orthogonal to each other. Further variations onthese codes are also possible. For example, the periodic pattern can bea linear sawtooth, quadratic sawtooth, cubic sawtooth, sinusoidal, orhave some other profile.

After the combined signal with the codes c₁ and c₂ has been transmitted,reflected, and received, the codes can be used to identify the time oftransmission of a received reflected beam. Similar analysis can also beapplied to the received signal as in the superheterodyne processdescribed above, such as Doppler frequency estimation and tracking, andcomparing the phase of the received beam with the transmitted beam toreduce noise.

The reflected beam received by the lidar sensor in FIG. 6A can also beused to measure a variety of features relating to an object at the pointof reflection, as discussed in other embodiments above. However, therecan be some differences.

For example, in the previously described method the distance can bedetermined using the difference in phases of the light fields of thetransmitted and received reflected beams (after demodulating thereceived reflected beam to remove the codes). Although that previouslydescribed method could also potentially be used in the system of FIG.6A, use of the periodicity of the sawtooth ramp code is described here.The relative phase Φ_(r) measured at the optical sensor 1801 at time tis equal to the phase of the modulation ramp at a time t−2L/c:

Φ_(r)(t)=Φ_(m)(t−2L/c)

where L is the distance to the object and c is the speed of light. Thetime of flight 2L/c and thus the distance LL can be derived by simplyinverting the phase of the modulation ramp code Φ_(m). Similarly, theradial velocity of the point of reflection can be computed using thedifference in phases of the transmitted and received reflected beamsafter decoding. The angular velocity can be computed using similarmethods to those discussed above.

The reflected beam can also be used to measure a reflectivity of theobject at the point of reflection. The quadrature amplitude of the DCsignal resulting from the reflected beam at the optical sensor can becompared with experimental results at comparable distances, usinglook-up tables for example, to determine a reflectivity.

Further, reducing the slope of the sawtooth phase profile at themodulator allows mapping of the surface microscopic profile of thetarget object onto the measured phase of the light.

Further variations on the design of the lidar sensor 100I are alsopossible, as shown in FIGS. 6B and 6C, which can be similar to theembodiment in FIG. 6A unless indicated to the contrary, with similarnames and reference numbers indicating similar components. For example,as shown in FIG. 6B, the lidar sensor 100J can include only one phasemodulator 150J. A first portion of the initial beam of light can passthrough the phase modulator 150J, and three optical circulators 190J,191J, 192J, as in FIG. 6A. A second portion of the initial beam of lightcan be directed through the phase modulator 150J in a reverse directionand then directed through an optional delay line 200J using the firstoptical circulator 190J. This delay can lead the second portion to havea code that is orthogonal to the first portion's code when they arerecombined. It should be noted that this lidar 100J is substantiallysimilar to the lidar 100B depicted in FIG. 5B (without a frequencyshifter). The phase modulation provided by the phase modulator 150J canoptionally include a pseudo-random binary code combined with a parabolicsawtooth pattern, as depicted in FIG. 7B.

FIG. 6C depicts an embodiment lidar sensor 100K similar to the lidarsensor 100I in FIG. 6A, with some minor differences. For example, atransceiver 120K/130K can replace the separate components in FIG. 6A.

As in the superheterodyne examples depicted in FIGS. 5A-5H, additionalvariations on the superhomodyne lidar sensors can also be provided. Forexample, the first portion and second portion can be separated usingfiber-optic fiber couplers or partially-reflective in-lineretroreflectors. These can be routed along separate paths or can becombined in a single path. They can also optionally be provided with thesame code.

FIGS. 9-11 depict various methods for measuring distances, which can beoptionally implemented using the systems described above. As shown inFIG. 9, an initial beam (such as a beam generated from a laser 110) canbe split into a transmitted portion and an internal portion. Thetransmitted portion can have its phase modulated to embed a unique code(as discussed above) prior to being directed into the environment. Thereceived reflected beam resulting from the transmitted portion can thenbe identified by detecting the unique code. The distance to a point ofreflection can then be estimated using the reflected beam and theinternal portion.

The method depicted in FIG. 10 is substantially similar to that in FIG.9, but shows that two separate transmitted portions can be used todetect distances simultaneously. The method depicted in FIG. 11 is alsosimilar to that in FIGS. 9 and 10, but shows that multiple values can beestimated, such as the radial and angular velocities, in addition to thedistance.

According to one embodiment, the techniques described herein (such asfor measuring distances, velocities, and reflectivities) are implementedby at least one computing device. The techniques may be implemented inwhole or in part using a combination of at least one server computerand/or other computing devices that are coupled using a network, such asa packet data network. The computing devices may be hard-wired toperform the techniques, or may include digital electronic devices suchas at least one application-specific integrated circuit (ASIC) or fieldprogrammable gate array (FPGA) that is persistently programmed toperform the techniques, or may include at least one general purposehardware processor programmed to perform the techniques pursuant toprogram instructions in firmware, memory, other storage, or acombination. Such computing devices may also combine custom hard-wiredlogic, ASICs, or FPGAs with custom programming to accomplish thedescribed techniques. The computing devices may be server computers,workstations, personal computers, portable computer systems, handhelddevices, mobile computing devices, wearable devices, body mounted orimplantable devices, smartphones, smart appliances, internetworkingdevices, autonomous or semi-autonomous devices such as robots orunmanned ground or aerial vehicles, any other electronic device thatincorporates hard-wired and/or program logic to implement the describedtechniques, one or more virtual computing machines or instances in adata center, and/or a network of server computers and/or personalcomputers.

FIG. 8 is a block diagram that illustrates an example computer systemwith which an embodiment may be implemented. In the example of FIG. 3, acomputer system 300 and instructions for implementing the disclosedtechnologies in hardware, software, or a combination of hardware andsoftware, are represented schematically, for example as boxes andcircles, at the same level of detail that is commonly used by persons ofordinary skill in the art to which this disclosure pertains forcommunicating about computer architecture and computer systemsimplementations.

Computer system 300 includes an input/output (I/O) subsystem 302 whichmay include a bus and/or other communication mechanism(s) forcommunicating information and/or instructions between the components ofthe computer system 300 over electronic signal paths. The I/O subsystem302 may include an I/O controller, a memory controller and at least oneI/O port. The electronic signal paths are represented schematically inthe drawings, for example as lines, unidirectional arrows, orbidirectional arrows.

At least one hardware processor 304 is coupled to I/O subsystem 302 forprocessing information and instructions. Hardware processor 304 mayinclude, for example, a general-purpose microprocessor ormicrocontroller and/or a special-purpose microprocessor such as anembedded system or a graphics processing unit (GPU) or a digital signalprocessor or ARM processor. Processor 304 may comprise an integratedarithmetic logic unit (ALU) or may be coupled to a separate ALU.

Computer system 300 includes one or more units of memory 306, such as amain memory, which is coupled to I/O subsystem 302 for electronicallydigitally storing data and instructions to be executed by processor 304.Memory 306 may include volatile memory such as various forms ofrandom-access memory (RAM) or other dynamic storage device. Memory 306also may be used for storing temporary variables or other intermediateinformation during execution of instructions to be executed by processor304. Such instructions, when stored in non-transitory computer-readablestorage media accessible to processor 304, can render computer system300 into a special-purpose machine that is customized to perform theoperations specified in the instructions.

Computer system 300 further includes non-volatile memory such as readonly memory (ROM) 308 or other static storage device coupled to I/Osubsystem 302 for storing information and instructions for processor304. The ROM 308 may include various forms of programmable ROM (PROM)such as erasable PROM (EPROM) or electrically erasable PROM (EEPROM). Aunit of persistent storage 310 may include various forms of non-volatileRAM (NVRAM), such as FLASH memory, or solid-state storage, magnetic diskor optical disk such as CD-ROM or DVD-ROM, and may be coupled to I/Osubsystem 302 for storing information and instructions. Storage 310 isan example of a non-transitory computer-readable medium that may be usedto store instructions and data which when executed by the processor 304cause performing computer-implemented methods to execute the techniquesherein.

The instructions in memory 306, ROM 308 or storage 310 may comprise oneor more sets of instructions that are organized as modules, methods,objects, functions, routines, or calls. The instructions may beorganized as one or more computer programs, operating system services,or application programs including mobile apps. The instructions maycomprise an operating system and/or system software; one or morelibraries to support multimedia, programming or other functions; dataprotocol instructions or stacks to implement TCP/IP, HTTP or othercommunication protocols; file format processing instructions to parse orrender files coded using HTML, XML, JPEG, MPEG or PNG; user interfaceinstructions to render or interpret commands for a graphical userinterface (GUI), command-line interface or text user interface;application software such as an office suite, internet accessapplications, design and manufacturing applications, graphicsapplications, audio applications, software engineering applications,educational applications, games or miscellaneous applications. Theinstructions may implement a web server, web application server or webclient. The instructions may be organized as a presentation layer,application layer and data storage layer such as a relational databasesystem using structured query language (SQL) or no SQL, an object store,a graph database, a flat file system or other data storage.

Computer system 300 may be coupled via I/O subsystem 302 to at least oneoutput device 312. In one embodiment, output device 312 is a digitalcomputer display. Examples of a display that may be used in variousembodiments include a touch screen display or a light-emitting diode(LED) display or a liquid crystal display (LCD) or an e-paper display.Computer system 300 may include other type(s) of output devices 312,alternatively or in addition to a display device. Examples of otheroutput devices 312 include printers, ticket printers, plotters,projectors, sound cards or video cards, speakers, buzzers orpiezoelectric devices or other audible devices, lamps or LED or LCDindicators, haptic devices, actuators or servos.

At least one input device 314 is coupled to I/O subsystem 302 forcommunicating signals, data, command selections or gestures to processor304. Examples of input devices 314 include the optical sensors and othersensors described herein, and potentially other devices such as touchscreens, microphones, still and video digital cameras, alphanumeric andother keys, keypads, keyboards, graphics tablets, image scanners,joysticks, clocks, switches, buttons, dials, slides, and/or varioustypes of sensors such as force sensors, motion sensors, heat sensors,accelerometers, gyroscopes, and inertial measurement unit (IMU) sensorsand/or various types of transceivers such as wireless, such as cellularor Wi-Fi, radio frequency (RF) or infrared (IR) transceivers and GlobalPositioning System (GPS) transceivers.

Another type of input device is a control device 316, which may performcursor control or other automated control functions such as navigationin a graphical interface on a display screen, alternatively or inaddition to input functions. Control device 316 may be a touchpad, amouse, a trackball, or cursor direction keys for communicating directioninformation and command selections to processor 304 and for controllingcursor movement on display 312. The input device may have at least twodegrees of freedom in two axes, a first axis (e.g., x) and a second axis(e.g., y), that allows the device to specify positions in a plane.Another type of input device is a wired, wireless, or optical controldevice such as a joystick, wand, console, steering wheel, pedal,gearshift mechanism or other type of control device. An input device 314may include a combination of multiple different input devices, such as avideo camera and a depth sensor.

In another embodiment, computer system 300 may comprise an internet ofthings (IoT) device in which one or more of the output device 312, inputdevice 314, and control device 316 are omitted. Or, in such anembodiment, the input device 314 may comprise one or more cameras,motion detectors, thermometers, microphones, seismic detectors, othersensors or detectors, measurement devices or encoders and the outputdevice 312 may comprise a special-purpose display such as a single-lineLED or LCD display, one or more indicators, a display panel, a meter, avalve, a solenoid, an actuator or a servo.

When computer system 300 is a mobile computing device, input device 314may comprise a global positioning system (GPS) receiver coupled to a GPSmodule that is capable of triangulating to a plurality of GPSsatellites, determining and generating geo-location or position datasuch as latitude-longitude values for a geophysical location of thecomputer system 300. Output device 312 may include hardware, software,firmware and interfaces for generating position reporting packets,notifications, pulse or heartbeat signals, or other recurring datatransmissions that specify a position of the computer system 300, aloneor in combination with other application-specific data, directed towardhost 324 or server 330.

Computer system 300 may implement the techniques described herein usingcustomized hard-wired logic, at least one ASIC or FPGA, firmware and/orprogram instructions or logic which when loaded and used or executed incombination with the computer system causes or programs the computersystem to operate as a special-purpose machine. According to oneembodiment, the techniques herein are performed by computer system 300in response to processor 304 executing at least one sequence of at leastone instruction contained in main memory 306. Such instructions may beread into main memory 306 from another storage medium, such as storage310. Execution of the sequences of instructions contained in main memory306 causes processor 304 to perform the process steps described herein.In alternative embodiments, hard-wired circuitry may be used in place ofor in combination with software instructions.

The term “storage media” as used herein refers to any non-transitorymedia that store data and/or instructions that cause a machine tooperation in a specific fashion. Such storage media may comprisenon-volatile media and/or volatile media. Non-volatile media includes,for example, optical or magnetic disks, such as storage 310. Volatilemedia includes dynamic memory, such as memory 306. Common forms ofstorage media include, for example, a hard disk, solid state drive,flash drive, magnetic data storage medium, any optical or physical datastorage medium, memory chip, or the like.

Storage media is distinct from but may be used in conjunction withtransmission media. Transmission media participates in transferringinformation between storage media. For example, transmission mediaincludes coaxial cables, copper wire and fiber optics, including thewires that comprise a bus of I/O subsystem 302. Transmission media canalso take the form of acoustic or light waves, such as those generatedduring radio-wave and infra-red data communications.

Various forms of media may be involved in carrying at least one sequenceof at least one instruction to processor 304 for execution. For example,the instructions may initially be carried on a magnetic disk orsolid-state drive of a remote computer. The remote computer can load theinstructions into its dynamic memory and send the instructions over acommunication link such as a fiber optic or coaxial cable or telephoneline using a modem. A modem or router local to computer system 300 canreceive the data on the communication link and convert the data to aformat that can be read by computer system 300. For instance, a receiversuch as a radio frequency antenna or an infrared detector can receivethe data carried in a wireless or optical signal and appropriatecircuitry can provide the data to I/O subsystem 302 such as place thedata on a bus. I/O subsystem 302 carries the data to memory 306, fromwhich processor 304 retrieves and executes the instructions. Theinstructions received by memory 306 may optionally be stored on storage310 either before or after execution by processor 304.

Computer system 300 also includes a communication interface 318 coupledto bus 302. Communication interface 318 provides a two-way datacommunication coupling to network link(s) 320 that are directly orindirectly connected to at least one communication networks, such as anetwork 322 or a public or private cloud on the Internet. For example,communication interface 318 may be an Ethernet networking interface,integrated-services digital network (ISDN) card, cable modem, satellitemodem, or a modem to provide a data communication connection to acorresponding type of communications line, for example an Ethernet cableor a metal cable of any kind or a fiber-optic line or a telephone line.Network 322 broadly represents a local area network (LAN), wide-areanetwork (WAN), campus network, internetwork or any combination thereof.Communication interface 318 may comprise a LAN card to provide a datacommunication connection to a compatible LAN, or a cellularradiotelephone interface that is wired to send or receive cellular dataaccording to cellular radiotelephone wireless networking standards, or asatellite radio interface that is wired to send or receive digital dataaccording to satellite wireless networking standards. In any suchimplementation, communication interface 318 sends and receiveselectrical, electromagnetic or optical signals over signal paths thatcarry digital data streams representing various types of information.

Network link 320 typically provides electrical, electromagnetic, oroptical data communication directly or through at least one network toother data devices, using, for example, satellite, cellular, Wi-Fi, orBLUETOOTH technology. For example, network link 320 may provide aconnection through a network 322 to a host computer 324.

Furthermore, network link 320 may provide a connection through network322 or to other computing devices via internetworking devices and/orcomputers that are operated by an Internet Service Provider (ISP) 326.ISP 326 provides data communication services through a world-wide packetdata communication network represented as internet 328. A servercomputer 330 may be coupled to internet 328. Server 330 broadlyrepresents any computer, data center, virtual machine or virtualcomputing instance with or without a hypervisor, or computer executing acontainerized program system such as DOCKER or KUBERNETES. Server 330may represent an electronic digital service that is implemented usingmore than one computer or instance and that is accessed and used bytransmitting web services requests, uniform resource locator (URL)strings with parameters in HTTP payloads, API calls, app services calls,or other service calls. Computer system 300 and server 330 may formelements of a distributed computing system that includes othercomputers, a processing cluster, server farm or other organization ofcomputers that cooperate to perform tasks or execute applications orservices. Server 330 may comprise one or more sets of instructions thatare organized as modules, methods, objects, functions, routines, orcalls. The instructions may be organized as one or more computerprograms, operating system services, or application programs includingmobile apps. The instructions may comprise an operating system and/orsystem software; one or more libraries to support multimedia,programming or other functions; data protocol instructions or stacks toimplement TCP/IP, HTTP or other communication protocols; file formatprocessing instructions to parse or render files coded using HTML, XML,JPEG, MPEG or PNG; user interface instructions to render or interpretcommands for a graphical user interface (GUI), command-line interface ortext user interface; application software such as an office suite,internet access applications, design and manufacturing applications,graphics applications, audio applications, software engineeringapplications, educational applications, games or miscellaneousapplications. Server 330 may comprise a web application server thathosts a presentation layer, application layer and data storage layersuch as a relational database system using structured query language(SQL) or no SQL, an object store, a graph database, a flat file systemor other data storage.

Computer system 300 can send messages and receive data and instructions,including program code, through the network(s), network link 320 andcommunication interface 318. In the Internet example, a server 330 mighttransmit a requested code for an application program through Internet328, ISP 326, local network 322 and communication interface 318. Thereceived code may be executed by processor 304 as it is received, and/orstored in storage 310, or other non-volatile storage for laterexecution.

The execution of instructions as described in this section may implementa process in the form of an instance of a computer program that is beingexecuted, and consisting of program code and its current activity.Depending on the operating system (OS), a process may be made up ofmultiple threads of execution that execute instructions concurrently. Inthis context, a computer program is a passive collection ofinstructions, while a process may be the actual execution of thoseinstructions. Several processes may be associated with the same program;for example, opening up several instances of the same program oftenmeans more than one process is being executed. Multitasking may beimplemented to allow multiple processes to share processor 304. Whileeach processor 304 or core of the processor executes a single task at atime, computer system 300 may be programmed to implement multitasking toallow each processor to switch between tasks that are being executedwithout having to wait for each task to finish. In an embodiment,switches may be performed when tasks perform input/output operations,when a task indicates that it can be switched, or on hardwareinterrupts. Time-sharing may be implemented to allow fast response forinteractive user applications by rapidly performing context switches toprovide the appearance of concurrent execution of multiple processessimultaneously. In an embodiment, for security and reliability, anoperating system may prevent direct communication between independentprocesses, providing strictly mediated and controlled inter-processcommunication functionality.

Further variations of lidar sensor systems and methods of using the sameare possible as described herein. As described above with respect toFIG. 1, a perception system, e.g., for an automobile, can include aplurality of probes 20, each of which can in turn include one or morelidar sensors. The probes may be connected to a central unit 10. Asshown, different ones of the probes 20 may be configured to sense, amongother things, distances of objects in different directions. In someembodiments, a lidar sensor may employ a light source, e.g., a laserthat is configured to emit a monochromatic beam of light at a singlewavelength. However, in some implementations, it may be moreadvantageous to employ a light source that is configured to emit lighthaving multiple discrete wavelengths. For example, when a source lighthaving a single wavelength is used in conjunction with multipletransceivers, the optical efficiency of sensing may degrade. In theseand various other circumstances, the inventors have discovered thatvarious advantages, including improved sensor efficiency and compacthardware, can be synergistically realized when the various lidar sensordesigns described herein are implemented with a light source configuredto provide beams of light having multiple wavelengths, as described inthe following. In the following, it will be understood that, while theconcept of using a light source having multiple wavelengths may bedescribed in conjunction with arrangements of components that may besimilar to some implementations of lidar sensors described above, it maybe implemented in conjunction with arrangements of components that maybe similar to any other implementations of lidar sensors describedabove, in which similar names and reference numbers indicate similarcomponents. As such, a detailed description of various arrangements ofcomponents according to some implementations of lidar sensors that canbe integrated with a light source configured to provide a source lighthaving multiple wavelengths may be omitted for brevity without loss ofenabling their implementations.

FIG. 12 illustrates a lidar sensor 100K configured to sense objectdistances using a source light having multiple wavelengths, according tosome embodiments. The lidar sensor 100K includes a light source 110Kconfigured to generate a source light having multiple differentwavelengths λ₁, λ₂, . . . λ_(n). The lidar sensor 100K additionallyincludes an optical synthesizer circuit 115B. The optical synthesizercircuit 115B is configured to receive a portion of the source lightcomprising light beams having different wavelengths. The opticalsynthesizer circuit 115B comprises a phase modulator 150B configured toembed a unique code into at least one of the light beams, in similarmanner as describe according to various embodiments described above. Thelidar sensor 100K further includes one or more transceivers120B-1/130B-1, 120B-2/130B-2, . . . 120B-n/130B-n configured to receivefrom the optical synthesizer circuit 115B at least one of code-embeddedlight beams having different wavelengths, to direct the at least one ofthe code-embedded light beams into an environment, and to receive atleast one of reflected light beams from objects reflecting the at leastone of the code-embedded light beams. As configured, the lidar sensor100K is configured to detect distances between the objects and thetransceivers using the at least one of the reflected light beams.

In some implementations, the light source 110K can be a light source,e.g., a laser, configured to emit a source light comprising light beamshaving multiple wavelengths in any one or more of the visible, infraredor ultraviolet spectra. Without limitation, the different wavelengthsmay include n number of wavelengths within a range of 1500 nm-1600 nm or1530 nm-1570 nm, where the different wavelengths may differ from eachother by at least 1 nm, e.g., 1-5 nm. In some other implementations, thelight source 110K can include multiple lasers configured to emit atwavelengths that are different from each other. In theseimplementations, the source light including multiple light beams havingdifferent wavelengths may initially pass through a wavelength splitter196 or a demultiplexer (DMUX) to be combined into a single light beambefore being received by the optical synthesizer circuit 115B. The nnumber of wavelengths can be, without limitation, any number between 1and 40, inclusive. As described herein, an optical synthesizer circuitrefers to an optical circuit optically connected to a light source and atransmitter, receiver or a transceiver. Examples of optical synthesizercircuits include various optical synthesizer circuits described abovewith respect to FIGS. 5A-5H and 6A-6C.

Still referring to FIG. 12, the optical synthesizer circuit 115B isconfigured to embed one or more unique codes into the portion of thesource light fed thereinto, which can in turn be split into furtherportions, as described above according to some embodiments. In theparticular embodiment illustrated in FIG. 12, in a similar manner asdescribed above with respect to FIG. 5B, the source light emitted by thelight source 110K can optionally encounter a wavelength splitter 196 ora DMUX, followed by a first fiber coupler 170B. The first fiber coupler170B can split direct an internal portion of the source light toward anoptical sensor 160B, and direct a remaining portion of the source lightto an optical synthesizer circuit 115B. The optical synthesizer circuit115B includes at least one phase modulator (depicted as an electro-opticmodulator, “EOM,” although other phase modulators are also possibleincluding, but not limited to dual-parallel Mach-Zehnderinterferometers) 150B, which is configured to apply a code to theportion of the source light fed into the optical synthesizer circuit115B comprising light beams having different wavelengths. The opticalsynthesizer circuit 115B may optionally include at least one frequencyshifter 140B (for instance an acousto-optic modulator, “AOM,” althoughother frequency shifters are also possible) to adjust the frequency ofthe portion of the source light fed into the optical synthesizer circuit115B comprising light beams having different wavelengths. The opticalsynthesizer circuit 115B can include a second fiber coupler 171Bconfigured to split the portion of the source light fed into the opticalsynthesizer circuit 115B into first and second portions fortransmission. The first portion can proceed directly to the frequencyshifter 140B, followed by a phase modulator 150B, followed by one ormore transceivers 120B-1/130B-1, 120B-2/130B-2, . . . 120B-n/130B-n in asubstantially similar manner as described above.

Still referring to FIG. 12, the lidar sensor 100K can include a firstoptical circulator 190B between the frequency shifter 140B and the phasemodulator 150B, a second optical circulator 191B between the phasemodulator and a third fiber coupler 172B, and a third optical circulator192B between the third fiber coupler 172B and the transceivers120B-1/130B-1, 120B-2/130B-2, . . . 120B-n/130B-n. The second portionsplit from the second fiber coupler 171B can be directed to the secondoptical circulator 191B, such that it passes through the phase modulator150B in reverse order relative to the first portion split from thesecond fiber coupler 171B. The second portion can then be directed bythe first optical circulator 190B to an optional delay line 200B,followed by the third fiber coupler 172B. The first portion and thesecond portion can be combined by the third fiber coupler 171B (servingas a combiner). Thus, both the first portion and the second portionsplit from the second fiber coupler 171B can be embedded with the uniquecode before being transmitted to the one or more transceivers120B-1/130B-1, 120B-2/130B-2, . . . 120B-n/130B-n, in a substantiallysimilar manner as described above.

In various embodiments, when there are n number of light beams havingdifferent wavelengths in the source light, at least two of the lightbeams can each be embedded with the unique code. In some embodiments,all of the light beams having different wavelengths can be embedded withthe unique code. However, embodiments are not so limited, and in otherembodiments, a subset of the light beams having different wavelengthscan be embedded with the unique code.

The code provided by the phase modulator 150B can be unique, such aswith a pseudo-random code as described above (although different typesof codes from spread spectrum theory can be used). This code can besufficiently random such that a delay provided by the delay line 200Bcan shift the codes applied to the first and second portions of the beamof light sufficiently for the two codes to be substantially orthogonalto each other. Thus, the processing of signals from the lidar sensor100K can be substantially similar to the lidar sensors described above,e.g., with respect to FIG. 5A, with the exception that f₂ is zero.Nevertheless, f₁ can optionally be adjusted in a similar manner toachieve the desired ambiguity range for the measured distance asdiscussed above with respect to FIG. 5A.

Still referring to FIG. 12, the lidar sensor 100K further includes oneor more transceivers 120B-1/130B-1, 120B-2/130B-2, . . . 120B-n/130B-nconfigured to receive from the optical synthesizer circuit 115B at leastone of the code-embedded light beams. When there are n number ofcode-embedded light beams having different wavelengths, the lidar sensor100K may include a corresponding n number of transceivers 120B-1/130B-1,120B-2/130B-2, . . . 120B-n/130B-n. In the illustrated embodiment, thecode-embedded light beams having different wavelengths can be split intoindividual wavelengths λ₁, Δ₂, . . . λ_(n) by the wavelengthcombiner-splitter 198 or a multiplexer (MUX)-demultiplexer (DMUX)(serving as a splitter or DMUX). After being split into light beamshaving single wavelengths, the individual ones of the code-embeddedlight beams are fed into corresponding ones of the transceivers120B-1/130B-1, 120B-2/130B-2, . . . 120B-n/130B-n, which in turn directthe code-embedded light beams into an environment. At least some of thecode-embedded light beams directed to the environment can be reflectedby object(s), and the transceivers 120B-1/130B-1, 120B-2/130B-2, . . .120B-n/130B-n are configured to receive at least one of reflected lightbeams from the object(s) reflecting the at least one of thecode-embedded light beams. One or more reflected light beams may then bereceived by the one or more transceivers 120B-1/130B-1, 120B-2/130B-2, .. . 120B-n/130B-n, which may be combined by the combiner-splitter 198 orMUX-DMUX (now serving as a combiner or MUX). The combined reflectedlight beam(s) may then be received by a third optical circulator 192B,which in turn directs the reflected light beam(s) to a fourth fibercoupler 193B. The fourth fiber coupler 193B combines the reflected lightbeam(s) and the internal portion of the source light split from thesecond fiber coupler 170B, and directs them to the optical sensor 160B,in a similar manner as described above, for identifying the reflectedlight beams and for detecting the distances of the object(s) in theenvironment.

In the illustrated embodiment in FIG. 12, each of the transceivers120B-1/130B-1, 120B-2/130B-2, . . . 120B-n/130B-n serve as both atransmitter and an emitter. However, embodiments are not so limited, andas described above with respect to FIG. 5A, the lidar sensor 100K canhave separate transmitters 120B-1, 120B-2, . . . 120B-n, and receivers130B-1, 130B-2, . . . 130B-n. When separate transmitters and receiversare present, after the code-embedded light beams are directed to theenvironment using transmitters 120B-1, 120B-2, . . . 120B-n, thereflected light beams may be received by the separate receivers 130B-1,130B-2, . . . 130B-n and directed to the optical sensor 160B thorough adifferent path, as shown in FIG. 5A, which may include a separatecombiner-splitter.

Advantageously, the inventors have discovered that, by using light beamshaving different wavelengths as shown in FIG. 12, the sensor efficiencyand signal-to-noise ratio may be significantly improved. In addition,because the same optical synthesizer circuit is used to embed a uniquecode into light beams having different wavelengths, compact hardware canbe synergistically realized, among other advantages.

FIGS. 13 and 14 illustrate lidar sensors 100L, 100M configured to senseobject distances using a source light having multiple wavelengths,according to some other embodiments. Various components of the lidarsensors 100L, 100M are similar or analogous to the correspondingcomponents described above with respect to FIG. 12 As such, a detaileddescription of the similar or analogous components is omitted herein forbrevity.

The lidar sensors 100L, 100M include a light source 110K configured togenerate a source light having different wavelengths λ₁, λ₂, . . .λ_(n), Similar to that described above with respect to FIG. 12. Unlikethe lidar sensor described above with respect to FIG. 12 in which thesame optical synthesizer circuit is used to embed a unique code intomultiple light beams having different wavelengths, each of the lidarsensors 100L, 100M includes a plurality of optical synthesizer circuits115B, where each of the optical synthesizer circuits 115B is configuredto receive a portion of one of the light beams having one of thewavelengths λ₁, λ₂, . . . λ_(n). In a similar manner as described abovewith respect to FIG. 12, each of the optical synthesizer circuits 115Bincludes a phase modulator 150B configured to embed a unique code intothe portion of the one of the light beams fed thereinto. The lidarsensor 100L additionally includes a plurality of transceivers120B-1/130B-1, 120B-2/130B-2, . . . 120B-n/130B-n each configured toreceive from a respective one of the optical synthesizer circuits 115Bone of code-embedded light beams, to direct the one of the code-embeddedlight beams into an environment, and to receive a reflected light beamfrom an object reflecting the one of the code-embedded light beams. Thelidar sensors 100L, 100M are configured, for each of the transceivers,to detect a distance between the object and the transceiver using thereflected light beam.

Now more in particular reference to the lidar sensor 100L illustrated inFIG. 13, when the light source 110K is configured to emit a source lightcomprising light beams having multiple wavelengths, e.g., amulti-wavelength laser, the source light from the light source 110K mayinitially pass through a wavelength splitter 196 to split the sourcelight into multiple light beams having different wavelengths for feedinginto the respective ones of the optical synthesizer circuits 115B.However, different from as shown in FIG. 13, when the light source 110Kcomprises multiple light sources each configured to emit a light beam ata wavelength, e.g., multiple lasers configured to emit at differentwavelengths, each light source may feed a light beam having a wavelengthdirectly into a respective one of the optical synthesizer circuit 115B.

Still referring to FIG. 13, each of the light beams having one of thewavelengths λ₁, λ₂, . . . λ_(n) is fed into a respective one of thesynthesizer circuits 115B, and thereafterwards, a unique code isembedded thereto, in a substantially similar manner as described above,e.g., with respect to FIGS. 5B and 12. Thereafterwards, n number ofcode-embedded light beams may be fed into a corresponding one of nnumber of transceivers 120B-11130B-1, 120B-2/130B-2, . . .120B-n/130B-n. Unlike the embodiment described above with respect toFIG. 12, the individual ones of the code-embedded light beams havingdiscrete wavelengths are fed into corresponding ones of the transceivers120B-1/130B-1, 120B-2/130B-2, . . . 120B-n/130B-n, which in turn directthe code-embedded light beams into an environment. At least some of thecode-embedded light beams directed to the environment can be reflectedby objects, and thereafterwards received by a corresponding ones of thethird optical circulators 192B, which is combined with the internalportion of the source light split from the first fiber coupler 170B,before being directed to corresponding ones of the optical sensors 160B,in a similar manner as described above with respect to FIGS. 5B and 12.

Now in reference to FIG. 14, the lidar sensor 100M is similar to thelidar sensor 100L described above with respect to FIG. 13 except,instead of each of the light beams having one of wavelengths λ₁, λ₂, . .. λ_(n) being split into a portion fed into an optical synthesizercircuit 115B and an internal portion by a first fiber coupler 170B afterthe source light is separated into individual light beams each having asingle wavelength, in the lidar sensor 100M, the first fiber coupler170B is positioned between the light source 110K and the splitter 196.As positioned, the first fiber coupler 170B is configured to separatethe source light, having multiple wavelengths, into portions fed intothe optical synthesizer circuits 115B and a common internal portion thatis transmitted directly to the fourth fiber coupler 193B followed by theoptical sensor 160B. In addition, unlike the lidar sensor 100L describedabove with respect to FIG. 13, after the code-embedded light beams aredirected to the environment and reflected by objects, all of thereflected beams having different wavelengths λ₁, λ₂, . . . λ_(n) aredirected into a combiner 198, before being combined with the commoninternal beam from the first fiber coupler 170B by the fourth fibercoupler 193B, and before being received by a common optical sensor 160B.

Thus, in the illustrated lidar sensors 100L, 100M in FIGS. 13 and 14,the portions of the source light beams having different wavelengths thatare fed into corresponding ones of the optical synthesizer circuits canbe embedded with a unique code in corresponding ones of the opticalsynthesizer circuits. In some embodiments, all of the light beams havingdifferent wavelengths can be embedded with the same unique code by theoptical synthesizer circuits. However, embodiments are not so limited,and in other embodiments, the light beams having different wavelengthscan be embedded with different unique codes.

In the illustrated lidar sensors in FIGS. 13 and 14, each of thetransceivers 120B-1/130B-1, 120B-2/130B-2, . . . 120B-n/130B-n serve asboth a transmitter and an emitter. However, embodiments are not solimited, and as described above with respect to FIG. 5A, the lidarsensor 100K can have separate transmitters 120B-1, 120B-2, . . . 120B-nand corresponding receivers 130B-1, 130B-2, . . . 130B-n. When separatetransmitters and receivers are present, after the code-embedded lightbeams are directed to the environment using transmitters 120B-1, 120B-2,. . . 120B-n, the reflected light beams may be received by the separatereceivers 130B-1, 130B-2, . . . 130B-n and directed to the opticalsensor 160B thorough a different path, as shown in FIG. 5A, which mayinclude a separate combiner-splitter.

Advantageously, the inventors have discovered that, by using light beamshaving different wavelengths as shown in FIGS. 13 and 14, the sensorefficiency and signal-to-noise ratio may be significantly improved,among other improvements. In addition, because different opticalsynthesizer circuits are used to embed a unique code into light beamshaving different wavelengths, the flexibility of embedding same ordifferent codes into the light beams can be synergistically realized,among other advantages.

While the inventive concepts of using a light source having multiplewavelengths have been described in reference to lidar sensors in FIGS.12-14 that are implemented with an optical synthesizer circuit 115Bsimilar to the optical synthesizer circuit 115B described above withrespect to FIG. 5B, embodiments are not limited. It will be appreciatedthat the concept of using a light source having multiple wavelengths canbe readily implemented in conjunction with any other lidar sensorarrangements described above with respect to FIGS. 5A-5H and 6A-6C, inwhich similar names and reference numbers may indicate similarcomponents. For example, the optical synthesizer circuits 192B describedabove with respect to FIGS. 12-14 may be replaced or used in conjunctionwith any of the corresponding optical synthesizer circuits describedabove with respect to FIGS. 5A-5H and 6A-6C. For example, the opticalsynthesizer circuit 115B may employ any of the configurations forembedding a unique code into a portion of the source light fed thereintoand/or for further splitting the portion of the source light into two ormore parts, among other various modifications to the light passingtherethrough. Furthermore, the concepts of using a light source havingmultiple wavelengths described in reference to FIGS. 12-14 can beimplemented in conjunction with any of the codes, systems and methodsdescribed throughout the application, including FIGS. 7A-11.

Some additional example embodiments are described in view of thefollowing clauses:

Clause 1. A lidar sensor comprising:

an optical sensor configured to produce signals based at least onreceiving one or more beams of light;

a laser configured to emit an initial beam of light, a first portion ofthe initial beam of light being directed into the environment and aninternal portion of the initial beam of light being directed to theoptical sensor, wherein the optical sensor is configured to receive boththe internal portion of the initial beam of light and a first reflectedbeam of light resulting from the first portion of the initial beam oflight being reflected at a first point of reflection in the environment;

a processor configured to:

-   -   receive signals from the optical sensor;    -   identify the first reflected beam of light as having resulted        from the first portion of the initial beam of light;    -   determine a distance to the point of reflection based at least        on the first reflected beam of light and the internal portion of        the initial beam of light;    -   determine a radial velocity of the point of reflection relative        to the lidar sensor based at least on a time derivative of a        difference in phases of the light field between the first        reflected beam of light and the internal portion of the initial        beam of light; and    -   determine an angular velocity of the point of reflection        relative to the lidar sensor based at least on a Doppler shift        of the first reflected beam of light and the determined radial        velocity.        Clause 2. The lidar sensor of clause 1, further comprising an        phase modulator configured to modulate a phase of the first        portion of the initial beam of light over a period of time with        a unique code to embed the unique code into a modulated phase of        the first portion of the initial beam of light prior to it being        directed into the environment.        Clause 3. The lidar sensor of clause 2, wherein the determined        distance is based at least on a time of return of the first        reflected beam of light using at least the unique code.        Clause 4. The lidar sensor of clause 1, wherein the lidar sensor        is configured to accurately determine distances over 10 meters.        Clause 5. The lidar sensor of clause 4, wherein the lidar sensor        is configured to accurately determine distances over 100 meters.        Clause 6. A lidar sensor comprising:

a laser configured to emit an initial beam of light;

a first fiber coupler in optical communication with the laser to receiveand divide the initial beam of light into a transmitted portion and aninternal portion;

an optical synthesizer circuit in optical communication with the firstfiber coupler to receive the transmitted portion of the initial beam oflight from the first fiber coupler and to adjust a phase of thetransmitted portion of the initial beam of light;

a transmitter in optical communication with the optical synthesizercircuit to receive the transmitted portion with an adjusted phase fromthe optical synthesizer circuit and direct the transmitted portion intothe environment;

a receiver configured to receive a reflected beam of light from theenvironment resulting from the transmitted portion of the initial beamof light;

a second fiber coupler in optical communication with the receiver andthe first fiber coupler to combine the reflected beam of light and theinternal portion of the initial beam of light into a combined beam oflight; and

an optical sensor in optical communication with the second fiber couplerto receive the second beam of light.

Clause 7. The lidar sensor of clause 6, wherein the transmitter andreceiver are a single transceiver.Clause 8. The lidar sensor of clause 6, wherein the optical synthesizercircuit comprises one or more phase modulators, the phase modulatorsbeing configured to embed a unique code into a modulated phase of thetransmitted portion of the initial beam of light.Clause 9. The lidar sensor of clause 8, wherein the one or more phasemodulators are also configured to embed a periodic pattern combined withthe unique code into the modulated phase of the transmitted portion ofthe initial beam of light.Clause 10. The lidar sensor of clause 6, wherein the optical synthesizercircuit further comprises at least two different optical paths and isconfigured to separate the transmitted portion of the initial beam oflight into a first portion and a second portion along the at least twodifferent optical paths and recombine the first portion and secondportion prior to being received by the transmitter.Clause 11. The lidar sensor of clause 10, wherein the opticalsynthesizer circuit comprises a third fiber coupler configured toseparate the transmitted portion of the initial beam of light into thefirst portion and the second portion, and a fourth fiber couplerconfigured to recombine the first portion and the second portion priorto being received by the transmitter.Clause 12. The lidar sensor of clause 10, wherein the opticalsynthesizer circuit comprises one or more phase modulators configured toembed different unique codes into modulated phases of each of the firstportion and the second portion prior to being recombined.Clause 13. The lidar sensor of clause 6, wherein the optical synthesizercircuit comprises a frequency shifter configured to adjust a frequencyof the transmitted portion of the initial beam of light prior to beingdirected into the environment.Clause 14. The lidar sensor of clause 6, wherein the lidar sensor isconfigured to accurately determine distances over 10 meters.Clause 15. The lidar sensor of clause 14, wherein the lidar sensor isconfigured to accurately determine distances over 100 meters.Clause 16. A method of operating a lidar sensor to measure a distance toan object and a velocity of the object, the method comprising:

splitting a beam of light into a transmitted portion and an internalportion;

directing the transmitted portion into the environment;

receiving a reflected beam resulting from the transmitted portion beingdirected into the environment;

estimating a distance to a point of reflection using the reflected beamand the internal portion;

estimating a radial velocity of the point of reflection relative to thelidar sensor based at least on a time derivative of a difference inphases of the light field between the reflected beam of light and theinternal portion; and

estimating an angular velocity of the point of reflection relative tothe lidar sensor based at least on a Doppler shift of the reflected beamand the determined radial velocity.

Clause 17. The method of clause 16, further comprising modulating aphase of the transmitted portion over a period of time with a uniquecode to embed the unique code into a modulated phase of the transmittedportion prior to it being directed into the environment.Clause 18. The method of clause 17, wherein the estimated distance isdetermined based at least on a time of return of the reflected beamusing at least the unique code.

What is claimed is:
 1. A lidar system comprising: a lidar sensorcomprising: an optical sensor configured to produce signals based atleast on receiving one or more beams of light; a laser configured toemit an initial beam of light, a first portion of the initial beam oflight being directed into an environment in a first direction and aninternal portion of the initial beam of light being directed to theoptical sensor, wherein the optical sensor is configured to receive boththe internal portion of the initial beam of light and a first reflectedbeam of light resulting from the first portion of the initial beam oflight being reflected at a first point of reflection in the environment;an optical element configured to divide the first portion into a firstpart and a second part prior to the first portion being directed intothe environment; at least one phase modulator configured to modulate aphase of at least the first part over a period of time with a firstunique code to embed the first unique code into a modulated phase of thefirst portion of the initial beam of light prior to the first portionbeing directed into the environment; and a transmitter configured todirect the first part and the second part to the environment.
 2. Thelidar system of claim 1, wherein the lidar system comprises a secondphase modulator configured to modulate a phase of the second part over aperiod of time with a second unique code to embed the second unique codeinto a modulated phase of the second part prior to it being directedinto the environment.
 3. The lidar system of claim 1, further comprisinga first optical frequency shifter configured to shift a frequency of atleast the first part by a first frequency shift prior to it beingdirected into the environment.
 4. The lidar system of claim 3, furthercomprising a delay line configured to delay the second part prior to itbeing directed into the environment.
 5. The lidar system of claim 3,wherein the at least one phase modulator comprises two phase modulators,wherein each of the first part and the second part is modulated by adifferent one of the two phase modulators, and wherein the second partis modulated by a second unique code prior to being directed into theenvironment.
 6. The lidar system of claim 4, wherein a same one of theat least one phase modulator is further configured to modulate a phaseof the second part over the period of time with the first unique code toembed the first unique code into a modulated phase of the second partprior to it being delayed.
 7. The lidar system of claim 5, furthercomprising a second optical frequency shifter configured to shift afrequency of the second part by a second frequency shift prior to itbeing directed into the environment.
 8. The lidar system of claim 5,wherein the first optical frequency shifter is further configured toshift a frequency of the second part prior to it being modulated by thesecond unique code.
 9. The lidar system of claim 3, wherein the at leastone phase modulator is further configured to modulate a phase of thesecond part over the period of time with the first unique code to embedthe first unique code into a modulated phase of the second part prior toit being directed into the environment and wherein the first opticalfrequency shifter is further configured to shift a frequency of thesecond part prior to it being modulated.
 10. The lidar system of claim8, wherein the optical element is a partial retroreflector.
 11. Thelidar system of claim 4, wherein the first optical frequency shifter isfurther configured to shift a frequency of the second part prior to itbeing delayed and wherein the at least one phase modulator is furtherconfigured to modulate a phase of the second part over the period oftime with the first unique code to embed the first unique code into amodulated phase of the second part prior to its frequency being shifted.12. The lidar system of claim 1, wherein the at least one phasemodulator is additionally configured to modulate a phase of the firstportion of the initial beam of light over the period of time with aperiodic pattern to embed the periodic pattern, combined with the firstunique code, into the modulated phase of the first portion of theinitial beam of light prior to it being directed into the environment.13. The lidar system of claim 1, further comprising at least one opticalfrequency shifter configured to shift a frequency of the first andsecond parts such that each of the first and second parts has adifferent frequency prior to being directed into the environment. 14.The lidar system of claim 1, wherein the laser is further configured toemit a second portion of the initial beam of light being directed intoan environment in a second direction different from the first direction.15. The lidar system of claim 14, wherein: the optical sensor isconfigured to receive a second reflected beam of light having resultedfrom the second portion being reflected at a second point of reflectionin the environment, and a time duration between the first portion of theinitial beam of light being directed into the environment and the firstreflected beam of light being received by the optical sensor overlapswith a time duration between the second portion of the initial beam oflight being directed into the environment and the second reflected beamof light being received by the optical sensor.
 16. The lidar system ofclaim 15, comprising a second phase modulator is configured to modulatea phase of the second portion over a second period of time with a secondunique code different from the first unique code to embed the secondunique code into a modulated phase of the second portion of the initialbeam of light prior to it being directed into the environment.
 17. Thelidar system of claim 1, further comprising a computing systemconfigured to receive the signals from the optical sensor and toidentify the first reflected beam of light as having resulted from thefirst portion based at least on detecting the first unique code, andfurther configured to determine a distance at least to the first pointof reflection based at least on the first reflected beam of light andthe internal portion of the initial beam of light.
 18. The lidar systemof claim 16, further comprising a computing system configured to:receive the signals from the optical sensor; identify the firstreflected beam of light as having resulted from the first portion basedat least on detecting the first unique code; determine a distance to thefirst point of reflection based at least on the first reflected beam oflight and the internal portion of the initial beam of light; identifythe second reflected beam of light as having resulted from the secondportion based at least on detecting the second unique code; anddetermine a distance to the second point of reflection based at least onthe second reflected beam of light and the internal portion of theinitial beam of light.
 19. The lidar system of claim 17, wherein thecomputing system is configured to determine the distance to the firstpoint of reflection based on at least a relative phase between the firstreflected beam of light and the internal portion of the initial beam oflight.
 20. The lidar system of claim 17, wherein the computing system isconfigured to determine the distance to the first point of reflectionbased on at least a time of return of the first reflected beam of lightusing at least the first unique code.
 21. The lidar system of claim 18,wherein the computing system is further configured to determine avelocity of the first point of reflection.
 22. The lidar system of claim21, wherein the velocity of the first point of reflection point is aradial velocity of the first point of reflection point relative to thelidar sensor, and wherein the computing system is configured todetermine the radial velocity of the first point of based at least on atime derivative of a difference in phases of light fields associatedwith the first reflected beam and the internal portion.
 23. The lidarsystem of claim 22, wherein the computing system is further configuredto determine an angular velocity of the first point of the reflectionbased at least in part on a Doppler shift of the first reflected beamand the radial velocity.
 24. The lidar system of claim 1, furthercomprising a receiver configured to receive at least the first reflectedbeam and direct the first reflected beam to the optical sensor.
 25. Thelidar system of claim 1, wherein the transmitter comprises a transceiverconfigured to: receive the first part and the second part from anoptical circulator; direct the first part and the second part to theenvironment; and receive at least the first reflected beam and directthe first reflected beam to the optical sensor.
 26. The lidar system ofclaim 17, wherein the lidar system is configured to recombine the firstpart and the second part of the first portion of the initial beam priorto it being directed into the environment, and wherein the transmitteris configured to direct the first part and the second part to theenvironment as a combined beam.
 27. The lidar system of claim 26,wherein the first reflected beam comprises a reflection of the combinedbeam at the first point of reflection and the computing system isconfigured to determine the distance to the first point of reflectionbased at least on a difference between a phase of a received syntheticbeam associated with the reflection of the combined beam and a phase ofa transmitted synthetic beam associated with the combined beam.
 28. Thelidar system of claim 26, wherein the first reflected beam, comprises areflection of the combined beam at the first point of reflection and thecomputing system is configured to determine a velocity of the firstpoint of reflection based at least on a time derivative of a differencebetween a phase of a received synthetic beam associated with the firstreflected beam and a phase of a transmitted synthetic beam associatedwith the combined beam.
 29. A lidar system comprising: a lidar sensorcomprising: an optical sensor configured to produce signals based atleast on receiving one or more beams of light; a laser configured toemit an initial beam of light, a first portion of the initial beam oflight being directed into an environment and an internal portion of theinitial beam of light being directed to the optical sensor, wherein theoptical sensor is configured to receive both the internal portion of theinitial beam of light and a first reflected beam of light resulting fromthe first portion of the initial beam of light being reflected at afirst point of reflection in the environment; an optical frequencyshifter configured to modulate a frequency of the first portion at afirst modulation frequency and a second modulation frequency, therebygenerating a dual frequency modulated beam; a phase modulator configuredto modulate a phase of the dual frequency modulated beam over a periodof time with a unique code to embed the unique code into a modulatedphase of the first portion of the initial beam of light prior to itbeing directed into the environment; and a transmitter configured todirect the first portion to the environment.
 30. The lidar system ofclaim 29, further comprising a computing system configured to receivethe signals from the optical sensor and to identify the first reflectedbeam of light as having resulted from the first portion based at leaston detecting the unique code, and further configured to determine adistance at least to the first point of reflection based at least on thefirst reflected beam of light and the internal portion of the initialbeam of light.